Yudong Huang

Hierarchical Proteinosomes for Programmed Release of Multiple Components

A facile route to hierarchically organized multicompartmentalized proteinosomes based on a recursive Pickering emulsion procedure using amphiphilic protein-polymer nanoconjugate building blocks is described. The number of incarcerated guest proteinosomes within a single host proteinosome is controlled, and enzymes and genetic polymers encapsulated within targeted subcompartments to produce chemically organized multi-tiered structures. Three types of spatiotemporal response-retarded concomitant release, synchronous release or hierarchical release of dextran and DNA-are demonstrated based on the sequential response of the host and guest membranes to attack by protease, or through variations in the positioning of disulfide-containing cross-links in either the host or guest proteinosomes integrated into the nested architectures. Overall, our studies provide a step towards the construction of hierarchically structured synthetic protocells with chemically and spatially integrated proto-organelles.

Hetero-epitaxially anchoring Au nanoparticles onto ZnO nanowires for CO oxidation

Supported Au nanoparticles (NPs) sinter easily. Anchoring Au NPs is of fundamental interest and practical importance. We stabilized Au NPs by growing them hetero-epitaxially into the facets of ZnO nanowires. The sintering of epitaxially anchored Au NPs was significantly reduced at high calcination temperatures and during CO oxidation.

Coordinated Membrane Fusion of Proteinosomes by Contact-Induced Hydrogel Self-Healing

Controlled membrane fusion of proteinosome-based protocells is achieved via a hydrogel-mediated process involving dynamic covalent binding, self-healing, and membrane reconfiguration at the contact interface. The rate of proteinosome fusion is dependent on dynamic Schiff base covalent interchange, and is accelerated in the presence of encapsulated glucose oxidase and glucose, or inhibited with cinnamyl aldehyde due to enzyme-mediated decreases in pH or competitive covalent binding, respectively. The coordinated fusion of the proteinosomes leads to the concomitant transportation and redistribution of entrapped payloads such as DNA and dextran. Silica colloids with amino-functionalized surfaces undergo partial fusion with the proteinosomes via a similar dynamic hydrogel-mediated mechanism. Overall, the strategy provides opportunities for the development of interacting colloidal objects, control of collective behavior in soft matter microcompartmentalized systems, and increased complexity in synthetic protocell communities.

Bio-inspired engineering proteinosomes with a cell-wall-like protective shell by self-assembly of a metal-chelated complex

A cell-wall-like shell is constructed around proteinosomes by coordination complexes of tannic acid and Fe3+, which endows the engineered proteinosomes with an enhanced Youngs modulus of the membrane, protease resistant ability, EDTA-mediated release of loaded DNA, and electrostatic gated encapsulated enzyme activity, as well as antioxidant capacity.

Construction of polymer coated core–shell magnetic mesoporous silica nanoparticles with triple responsive drug delivery

Multi-responsive drug delivery systems are playing a very important role in nanomedicine, as they can feature as smart carriers releasing their payload on demand. In this study, magnetic, reductive and thermo triple-responsive nanocarriers based on core–shell magnetic mesoporous silica nanoparticles (MMSNPs) modified with a thermo responsive polymer poly(N-isopropylacrylamide) (PNIPAAm) have been developed. Photoinduced electron/energy transfer-reversible addition fragmentation chain transfer (PET-RAFT) polymerization, mediated by a ruthenium-based photoredox Ru(bpy)3Cl2 catalyst was used to graft PNIPAAm onto MMSNPs. A series of characterization and testing techniques were applied to confirm the structures of the synthesized nanocarriers to assess their efficiency as drug delivery systems. Doxorubicin (DOX) was easily encapsulated into the nanocarriers with a high loading capacity, and quickly released in response to the triple-responsive systems. The MMSNPs remained intact in all synthetic steps, during the loading of the drug and the in vitro release tests. Thus, these multi responsive polymer grafted Fe3O4-capped-MSN models are not only magnetically guided, but also represent a promising candidate in the formulation of targeted delivery of therapeutic agents to temperature and more reductive environment tissues, such as tumors and inflammatory sites.

Design and Construction of Hybrid Microcapsules with Higher-Order Structure and Multiple Functions

Abstract The construction of inorganic‐protein hybrid microcapsules by using bovine serum albumin, metal ion clusters, and poly (N‐isopropylacrylamide) nanoconjugates as building blocks is presented. These microcapsules have robust membranes, which can keep their spherical morphology. They support interfacial catalytic activity by the ion clusters on their surface, and can be used as a platform to immobilize enzyme on the interface of oil/water to increase the diversity and efficiency of catalysis. These microcapsules also act as a container to make materials away from bacteria when existing silver clusters on the membrane. The obtained results highlight the construction of these microcompartments. These novel microcompartments can provide some new opportunities in bottom‐up synthetic biology, bioinspired microstorage/ microreactor, and drug/gene delivery in the future.

Anchoring Au Nanoparticles onto ZnO Nanowires by Heteroepitaxy

ZnO NWs were fabricated by a thermal evaporation-condensation method in a high-temperature tube furnace. The 2wt%Au/Zn Onanocatalysts were prepared by a deposition-precipitation method. The ZnO NW and powder supported Au catalysts are labeled as Au/ZnO-NW and Au/ZnO-P, respectively. The final catalysts were obtained by calcining the precursors at 400°C for 4 hours. The 5wt%Au/ZnO nanocatalysts calcined at 600°C were synthesized for XRD analysis. The catalytic performances of the prepared samples for CO oxidation were evaluated in a fixed-bed plug-flow reactor. Powder X-ray diffraction (XRD) patterns were taken on a PANalyticalX’pert PRO MRD X-ray diffractometer using Cu Ka radiation. The JEOL JEM-ARM200F aberration-corrected scanning transmission electron microscope (STEM), with a nominal image resolution of 0.08 nm in the high-angle annular dark-field (HAADF) imaging mode, was used to investigate the structure of the Au/ZnO catalysts.

ZnO Nanowire-supported Ag Catalyst for Methanol Steam Reforming

Alternative energy sources, such as various fuel cell technologies, have attracted intense attention due to their high efficiency and low emissions of pollutants. Methanol, with its high hydrogen/carbon ratio, low sulfur content and the absence of carbon–carbon bonds, has been identified as a highly suitable source for onboard production of hydrogen [1]. Among several reactions for converting methanol to H2, methanol steam reforming (MSR) is one of the most attractive processes because it can provide a high H2 content and an extremely low level of CO in the product [2]. We report here our recent study of Ag nanoparticles (NPS) supported on ZnO nanowires (NWs) as a catalyst for MSR reaction.

High-Contrast SEM Imaging of Supported Few-Layer Graphene for Differentiating Distinct Layers and Resolving Fine Features: There is Plenty of Room at the Bottom

For supported graphene, reliable differentiation and clear visualization of distinct graphene layers and fine features such as wrinkles are essential for revealing the structure-property relationships for graphene and graphene-based devices. Scanning electron microscopy (SEM) has been frequently used for this purpose where high-quality image contrast is critical. However, it is surprising that the effect of key imaging parameters on the image contrast has been seriously undermined by the graphene community. Here, superior image contrast of secondary electron (SE) images for few-layer graphene supported on SiC and SiO2 /Si is realized through simultaneously tuning two key parameters-acceleration voltage (Vacc ) and working distance (WD). The overlooked role of WD in characterizing graphene is highlighted and clearly demonstrated. A unified model of Vacc and WD dependence of three types of SE collected by the standard side-attached Everhart-Thornley (E-T) SE detector is conceptually developed for mechanistically understanding the improved mass thickness contrast for supported few-layer graphene. The findings reported here will have important implications for effective characterizations of atomically thick 2D materials and devices.